package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.dto.ScrollResult;
import com.hmdp.dto.UserDTO;
import com.hmdp.entity.Blog;
import com.hmdp.entity.Follow;
import com.hmdp.entity.User;
import com.hmdp.mapper.BlogMapper;
import com.hmdp.service.IBlogService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.service.IFollowService;
import com.hmdp.service.IUserService;
import com.hmdp.utils.SystemConstants;
import com.hmdp.utils.UserHolder;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ZSetOperations;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

import static com.hmdp.utils.RedisConstants.FEED_KEY;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class BlogServiceImpl extends ServiceImpl<BlogMapper, Blog> implements IBlogService {

    @Resource
    private IUserService userService;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private IFollowService followService;

    @Override
    public Result queryHotBlog(Integer current) {
        // 根据用户查询
        Page<Blog> page = query()
                .orderByDesc("liked")
                .page(new Page<>(current, SystemConstants.MAX_PAGE_SIZE));
        // 获取当前页数据
        List<Blog> records = page.getRecords();
        // 查询用户
        records.forEach(blog ->{
            this.queryBlogUser(blog);
            this.isBlogLike(blog);
        });
        return Result.ok(records);
    }

    @Override
    public Result likeBlog(Long id) {
        //获取登录用户
        Long userId = UserHolder.getUser().getId();
        //判断当前用户是否已经点赞
        String key = "blog:liked:"+id;//博客id
//        Boolean isMember = stringRedisTemplate.opsForSet().isMember(key, userId.toString());
//        if(BooleanUtil.isFalse(isMember)){
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());//新增点赞排行榜功能
        if(score == null){//分数为空
            //若未点赞，可以点赞
            //数据库点赞数+1
            boolean isSuccess = update().setSql("liked = liked + 1").eq("id", id).update();
            //保存用户到redis的set集合
            if (isSuccess){
//                stringRedisTemplate.opsForSet().add(key, userId.toString());
                stringRedisTemplate.opsForZSet().add(key, userId.toString(),System.currentTimeMillis());
            }
        }
        else {
            //若已经点赞，取消点赞
            //数据库点赞数-1
            boolean isSuccess = update().setSql("liked = liked - 1").eq("id", id).update();
            //把用户从redis的set集合中移除
//            stringRedisTemplate.opsForSet().remove(key, userId.toString());
            if(isSuccess){
                stringRedisTemplate.opsForZSet().remove(key, userId.toString());
            }
        }
        return Result.ok();
    }

    @Override
    public Result queryBlogLikes(Long id) {
        String key = "blog:liked:" + id;
        //查询top5的点赞用户
        Set<String> top5 = stringRedisTemplate.opsForZSet().range(key, 0, 4);
        if(top5 == null || top5.isEmpty()){
            return Result.ok(Collections.emptyList());
        }
        //解析出其中的用户id
        List<Long> ids = top5.stream().map(Long::valueOf).collect(Collectors.toList());
        //根据用户id查询用户
//        List<UserDTO> userDTOS = userService.listByIds(ids)//顺序
        String idStr = StrUtil.join(",", ids);
        List<UserDTO> userDTOS = userService.query()
                .in("id", ids).last("order by field(id,"+idStr+")").list()//逆序，实现显示最后点赞的五位用户
                .stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());

        //返回
        return Result.ok(userDTOS);
    }

    @Override
    public Result saveBlog(Blog blog) {
        // 获取登录用户
        UserDTO user = UserHolder.getUser();
        blog.setUserId(user.getId());
        // 保存探店博客
        boolean isSuccess = save(blog);
        if(!isSuccess){
            return Result.fail("新增笔记失败!");
        }
        //查询笔记作者的所有粉丝
        List<Follow> follows = followService.query().eq("follow_user_id", user.getId()).list();
        //推送笔记id给所有粉丝
        for(Follow follow : follows){
            //获取粉丝id
            Long userId = follow.getUserId();
            //推送
            String key = "feed:" + userId;
            //因为新增笔记会影响笔记列表的下标，传统分页查询(按下标)会造成重复查询的问题，不能满足需求
            //这里采用滚动分页查询 ———— 即不使用下标查询，改为使用时间戳查询
            //list集合只能通过下标查询，而SortSet(这里按时间戳排序(score值))还能通过时间戳查询
            stringRedisTemplate.opsForZSet().add(key, blog.getId().toString(),System.currentTimeMillis());
        }
        // 返回id
        return Result.ok(blog.getId());
    }

    @Override
    public Result queryBlogOfFollow(Long max, Integer offset) {
        //获取当前用户
        Long userId = UserHolder.getUser().getId();
        //查询收件箱
        String key = FEED_KEY + userId;
        Set<ZSetOperations.TypedTuple<String>> typedTuples = stringRedisTemplate.opsForZSet()
                .reverseRangeByScoreWithScores(key, 0, max, offset, 2);//带上分数翻转
        //非空判断
        if(typedTuples == null || typedTuples.isEmpty()){
            return Result.ok();
        }
        //解析数据blogId,minTime(时间戳),offset(集合中分数值等于最小时间的所有元素的个数)
        List<Long> ids = new ArrayList<>(typedTuples.size());
        long minTime = 0;
        int os = 1;
        for (ZSetOperations.TypedTuple<String> tuple : typedTuples){
            //获取id
            String idStr = tuple.getValue();
            ids.add(Long.valueOf(idStr));
            //获取分数(时间戳)
            long time = tuple.getScore().longValue();
            if(time == minTime){
                os++;
            }
            else {
                minTime = time;
                os = 1;
            }
        }
        //根据id查询blog
        String idStr = StrUtil.join(",", ids);
        List<Blog> blogs = query().in("id", ids).last("order by field(id," + idStr + ")").list();

        for (Blog blog : blogs){
            //查询博客用户
            queryBlogUser(blog);
            //查询笔记是否已被点赞
            isBlogLike(blog);
        }
        //封装并返回
        ScrollResult result = new ScrollResult();
        result.setList(blogs);
        result.setOffset(os);
        result.setMinTime(minTime);

        return Result.ok(result);
    }

    private void queryBlogUser(Blog blog) {
        Long userId = blog.getUserId();
        User user = userService.getById(userId);
        blog.setName(user.getNickName());
        blog.setIcon(user.getIcon());
    }

    @Override
    public Result queryBlogById(Long id) {
        //查询用户id
        Blog blog = getById(id);
        if(blog == null){
            return Result.fail("笔记不存在");
        }
        //查询博客用户
        queryBlogUser(blog);
        //查询笔记是否已被点赞
        isBlogLike(blog);
        return Result.ok(blog);
    }

    private void isBlogLike(Blog blog) {
        //用户未登录
        UserDTO user = UserHolder.getUser();
        if(user == null){
            return;
        }
        //获取登录用户
        Long userId = UserHolder.getUser().getId();
        //判断当前用户笔记是否已经点赞
        String key = "blog:liked:"+blog.getId(); //博客id
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        blog.setIsLike(score != null);
    }
}
